|Marriage and other
equivalent or similar unions and status
|Validity of marriages|
|Dissolution of marriages|
|Private international law|
|The Family and the Criminal Code
(or Criminal Law)
A void marriage is a marriage which is unlawful or invalid under the laws of the jurisdiction where it is entered. A void marriage is "one that is void and invalid from its beginning. It is as though the marriage never existed and it requires no formality to terminate." 
Most jurisdictions recognise the validity of marriages performed in another jurisiction. However, a jurisdiction where the parties to the marriage normally reside (and where recognition of the marriage has significant implications) may not recognise a "foreign" marriage and may declare it void - for example, a same-sex marriage, a group marriage and in some cases a polygamous marriage.
A marriage, however, which can be canceled at the option of one of the parties is merely voidable, meaning it is subject to cancellation if contested in court. A marriage that is entered into in good faith, but which is subsequently found to be void, may be recognized as a putative marriage and the spouses as putative spouses, with certain rights granted by statute or common law, notwithstanding that the marriage itself is void.
In general, a marriage is void (as opposed to voidable) if:
- The parties' degree of consanguinity is too close - for example, a brother and sister or a parent and a child. Different jurisdictions have different lists of prohibited incestuous relationship.
- A party to the marriage is forbidden to marry as a result of losing their civil rights, such as for conviction of a crime.
- The form of the marriage is forbidden by statute - such as same-sex marriage or group marriage.
- There is a pre-existing marriage by at least one of the parties, and the subsequent marriage may also constitute a crime of bigamy.
New York law
Under the Domestic Relations Law of New York state, all incestuous marriages are void, but this does not include cousin marriages of any degree:
- § 5. Incestuous and void marriages. A marriage is incestuous and void whether the relatives are legitimate or illegitimate between either:
- 1. An ancestor and a descendant;
- 2. A brother and sister of either the whole or the half blood;
- 3. An uncle and niece or an aunt and nephew.
- If a marriage prohibited by the foregoing provisions of this section be solemnized it shall be void...|N.Y. D.R.L., §5, found at 
- § 6. Void marriages. A marriage is absolutely void if contracted by a person whose husband or wife by a former marriage is living, unless either:
- 1. Such former marriage has been annulled or has been dissolved for a cause other than the adultery of such person; provided, that if such former marriage has been dissolved for the cause of the adultery of such person, he or she may marry again in the cases provided for in section eight of this chapter and such subsequent marriage shall be valid;
- 3. Such former marriage has been dissolved pursuant to section seven-a of this chapter. (This is regarding annulment of a voidable marriage.)| N.Y. D.R.L., §6, found at 
Under the law of the United Kingdom, a void marriage is "one that is considered never to have taken place, whatever procedure may have been followed by the people concerned."  Under the relevant law, the Matrimonial Causes Act 1973:
a marriage is void if ...
the partners are related in a forbidden degree (see: Marriage). For example, a marriage between brother and sister would be void. It does not matter if the partners did not know they were related when the ceremony was carried out (odd as it sounds, this has happened in adoption cases), either partner was under 16 years of age, the formal procedures of marriage were not correctly followed; for example, the wedding may not have been in a registered building, or open to the public,the partners were of the same gender at birth.